Research traces 50,000 years of change

New studies of fossils show how the impact on humans, especially due to the growth of agriculture and livestock, destroyed the natural communities of mammals as deeply as the extinction of the ice age.

Fossil bones from six continents showed how people mainly transformed mammals around the world, according to new research, which traces 50,000 years of animal history.

International research, Published Last month in Biological lettersIt shows that during the last glacial period of the mammalian community, various patterns on continents based on natural climatic zones and geographical barriers. But after agriculture began about 10,000 years ago, only a few types of livestock spread with people and pressed these natural boundaries forever.

“The study shows how agriculture and hunt combined as powerful global forces to reorganize ecosystems, which still create problems of preservation today,” says Associate Professor John Alroy from the University of McCaori, co-author of the study.

Researchers compared the lists of species from the last ice age, in particular, in the late pleistocene geological era, ending about 11,700 years ago – with the lists of the Holocene, our current era, which began when this ice age ended.

“We have studied lists of types of hundreds of archaeological and paleontological places on several continents covering the last 50,000 years,” says the leading author Barry Brooke, a biologist for the protection of the nature of Tasmania.

During the Pleistocene, natural factors, such as climate gradients, and physical barriers, such as mountain ranges and oceans, formed the composition of large mammalian communities. Animals in a similar climate had a tendency to live together, creating predictable continental models.

But Golucen caused dramatic changes in the distribution of species directly related to the human development of agriculture and domesticating certain species of animals.

Home violation

Studying archaeological notes, the researchers found that only 12 domesticated species, including cattle, sheep, pigs and horses, in about half the studied global places, which fundamentally changes the composition of animal communities.

“After the start of agriculture, only a few types of livestock spread with people, and incurred these natural boundaries, changing the mammals of mammals around the world,” says Professor Brook.

Domestic animals that had a huge impact included familiar agricultural animals.

“All domesticated species influenced, including donkeys, sheep, goats, pigs and dogs,” says Associate Professor Alroy. “Large leather leather, such as horses and cows, are important because they monopolize food resources, wherever they are in large quantities.”

While the study excluded birds from the main analysis due to their unstable fossil record, Associate Professor Alroy says that the domesticated chickens were also discovered in 29 out of 350 plots, mainly in Europe and the Middle East.

Researchers have developed a new computer clustering method to show that domesticated animals connect holocene archaeological places thousands of kilometers from each other. At the same time, many wild mammals died out, in each case after the arrival of a person, and not all over the world of an episode to change the climate.

When domesticated animals were common among geographically distant regions, these ecosystems turned out to be the same compositions. For example, mammals communities in Europe and Africa became more similar after both adopted domesticated species from the Middle East.

Behind megafauna

While the impact on a person was discovered almost everywhere, the Pleistocene extinction was more serious in regions with a smaller evolutionary history between people and Local speciesSuch as North and South America, Australia, New Zealand and Madagascar.

After the Pleistocene, the influence of agriculture also changed dramatically depending on the region. In some areas, such as the new Guinea and Sri -Lanka, they survived minimal changes, while in Europe, America, Australia and some parts of Africa there were the highest levels of circulation of species, which led to the greatest loss and increase in various species of animals.

Previous studies of the disappearance of the late ice age were emphasized by the disappearance of large “megafauna”-ill animals, such as giant sloths, woolly mammoths and giant marsupials, but this study shows Human impact Continuation for a long time after their disappearance.

“When Megafauna, such as mammoth, disappeared, we expected that the lack of competition for food would see that surviving wild species increase their size of the population, but this did not happen,” says Professor Alroy, assistant professor.

Clastorization shows the distribution of species

Using a new method called “CHASE CLSSE”, the team grouped fossils based on lists containing very similar species, regardless of where the sites are geographically.

“Groups of domesticated animals connect areas of thousands of kilometers from each other, while many wild mammals in these areas have disappeared,” says Associate Professor Alroy.

Typically, areas close to geographically have similar animals from the general climate and the environment. But the new method revealed something missed by traditional methods: human activity has broken this model, spreading the same agricultural animals.

Associate Professor Alroy says this study shows that the Chase clustering method can be widely used in studies regarding fossils.

Modern consequences

Some researchers associate past species, deep in the history of the Earth with human hunting or major changes in the climate, despite the fact that significant climate changes in the playwoodsen are either mostly useful for mammals, or do not coincide with extinction.

Nevertheless, this study shows that the extinction of species of playistots related to hunting was supplemented by very different agricultural influences in the Golocene.

“Over the past 10,000 years, people have observed the wholesale replacement of local mammals of mammals with a very limited set of domesticated species,” says Associate Professor Alroy.

“The ecosystems after distortion have not been truly natural over the past 10,000 years or more, so national parks in the most difficult regions, such as Australia and America, lacks half of the major natives mammal Types that would be present if not for people. “

It gives a dramatic example from Australia: “One layer of excavations in the hard entrance cave in Western Australia includes 17 types of large mammals, including tilacin, Tasmansk Devil, Tilacoleo, Zigomatus, large, faded into -brown and five different types of extinct short -range gangaras, not perceived by the ecosystem, not perceived compared to compared to with modern. “

This content was originally published at the University of McCaori LighthouseField